Asymmetry of the Face in Orthodontic Patients

Abstract

Objective: To investigate the laterality of the normal asymmetry of the human face, examining differences in laterality in relation to sex, growth stage, and skeletal classification. Materials and Methods: A total of 1800 Japanese subjects (651 males and 1149 females; mean age, 15 years 3 months; range, 4 years 2 months to 59 years 11 months) were selected. Individuals in the sample were categorized according to sex, one of three growth stages, and one of three skeletal patterns. Differences in length between distances from the points at which ear rods were inserted to the facial midline and the perpendicular distance from the soft-tissue menton to the facial midline were measured on a frontal facial photograph. Subjects with a discrepancy of more than 3 standard deviations of the measurement error were categorized as having left-or right-sided laterality. Results: Of subjects with facial asymmetry, 79.7% had a wider right hemiface, and 79.3% of those with chin deviation had left-sided laterality. These tendencies were independent of sex, age, or skeletal jaw relationships. In this regard, during pubertal growth, the proportion of subjects with wider right hemiface decreased (P Ͻ .0001), whereas the proportion of those with a wider left hemiface increased (P Ͻ .01), despite a consistent tendency for right-sided dominance. Conclusion: These results suggest that laterality in the normal asymmetry of the face, which is consistently found in humans, is likely to be a hereditary rather than an acquired trait.

Laterality of Asymmetry in Movements of the Corners of the Mouth during Voluntary Smile

“…Numerous studies [26][27][28] have reported that the righthemiface tends to be wider than the left. The size difference between the right and left hemiface is suggested as one possible cause of the asymmetric displacements of the right and left corners of the mouth during voluntary smile.…”

Orthodontic approach to treatment of skeletal mandibular asymmetry: A case report

“…Perfectly symmetric faces, constructed in computer software, are unnatural and are not as beautiful as the natural asymmetric ones [7]. It is known that a certain degree of asymmetry is beautiful, but the border line between normal asymmetry and asymmetry that requires treatment is subjective [8] and varies among professionals and lay people [6].…”

Exclusion ofpituitary homeobox 2gene polymorphism in vertical mandibular asymmetry patients: a preliminary study

“…Any dental treatment during growth period might influence the downward and forward mandible growth potential. The displacement of the mandible towards the affected side such as asymmetric condylar growth could happen [2,3,7].…”

“…One of the common craniofacial deformities is an asymmetric growth of the mandible or other diseases affecting the facial growth. It has a direct impact to aesthetic concern and functional problems of the stomatognathic system [1,2]. Factors potentially contributing to this individual masticatory action variation is related to the consistency of the diet and genetic predisposition that seems to be direct consequences of malfunction at the cellular level of condylar cartilage [3].…”

“…The panoramic radiograph is relatively accessible and provides the bilateral view of the mandible compared other radiograph. Then, the panoramic radiograph can be used to evaluate condylar mandibular asymmetry with 6% difference by Habets' formula and 93% difference by Kjellberg's technique [2,7,18,19]. Several authors have used this method to assess mandibular asymmetry in patients with temporomandibular disorders (TMD), unilateral and bilateral posterior crossbites, various sagittal malocclusions, and cleft lip and palate [7,20,21].…”